The present invention relates to an image reading device, and a method for controlling a sheet feed to be employed in the image reading device such as a copying machine, facsimile machine, scanning machine or the like.
An image reading device is employed in various apparatuses as described above. For example, there has been known a facsimile apparatus having a main body provided with a transparent surface on a top surface thereof, and a cover which is swingablly secured on the main body to cover/uncover the transparent surface. When the facsimile apparatus is used to read an original, the original is placed on the transparent surface and the image sensor is moved to scan an entire surface of the sheet placed on the transparent surface. This type of the facsimile apparatus is well-known as a flat-bed type apparatus.
There has been known an improved facsimile apparatus which has, in addition to the above structure, an automatic sheet feeding mechanism provided to the cover. The automatic sheet feeding mechanism functions to feed a plurality of sheets, which are placed on a sheet tray formed on the cover in a stacked manner, one by one. The sheet fed by the sheet feeding mechanism is fed along a sheet feed path, which is defined in the cover. The sheet feeding path is configured such that the sheet being fed is exposed to the image sensor at an intermediate portion thereof. Thus, the sheet fed from the sheet tray is fed past the image sensor located at a predetermined position, thereby an image formed on the sheet being scanned. The sheet is further fed along the remaining portion of the sheet feed path defined inside the cover, and is finally discharged therefrom.
In such a facsimile apparatus, if the cover is opened when a sheet is being fed, the sheet feeding operation should be temporarily terminated until the cover is closed. However, depending on the location of the sheet, a part of the sheet may hang from the opened cover. If the cover is closed in such a status, a part of the sheet may be caught by a nip between the cover and the main body. If the sheet feeding mechanism is actuated in such a condition, a sheet jam may occur.
Generally, sheet sensors are provided in the cover to detect a location of the sheet fed through the sheet feeding path. Such sensors should be configured not to obstacle the movement of the sheet. For this purpose, each sensor is configured to have a driven member which can easily be driven by the sheet to detect the presence of the sheet. Due to such a configuration, however, the driven member is easily driven by a vibration which is caused when the cover is opened and/or closed. If the sensors erroneously function, the location of the sheet and/or occurrence of the sheet jam cannot be detected accurately.